1. Field
The present disclosure relates generally to composite components and in particular to a method and apparatus for manufacturing composite components. Still more particularly, the present invention relates to a method and apparatus for fastening composite components to each other using a composite fastening system.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than fifty percent of their primary structure made from composite materials. Composite materials are being used in aircraft to decrease the weight of the aircraft. This decreased weight improves payload capacities and fuel efficiencies. Further, composite materials also may provide improved corrosion and fatigue resistance for various components in an aircraft thereby contributing to the overall improvement of the aircraft performance.
Composite materials are tough, light-weight materials created by combining two or more dissimilar components to create a component with stronger properties than the original materials. Composite materials are also typically non-metallic materials. In these examples, a composite is a multi-phase material, in which the phase distribution and geometry may have been controlled to optimize one or more properties.
One phase is typically continuous and referred to as a matrix. The matrix may be typically more compliant than other phases and may be tougher than other phases. This matrix typically supports and binds the reinforcement together and provides environmental protection for the reinforcement. The matrix may transmit the load from one piece of reinforcement to the other, usually by shear, and may carry shear stresses of the composite. Other phases may be distributed within the matrix and are often fibrous or particulates. These distributed phases are often stiffer and stronger than the matrix and may provide the composite with its high stiffness and strength properties. For example, a composite may include fibers and resins.
Fibers that may be found in composites include, for example, graphite, boron, high-tensile glass, ceramic, and aramid used in conjunction with polyester/vinyl-ester, epoxy, ceramic, and metal matrixes. The fibers and resins may be combined by curing or heating these constituents to form a cured material or product for the composite component.
In manufacturing aircraft, various two-piece metallic fastening systems have been long used for the assembly of aircraft structures and components of all types of metallic or non-metallic materials. Typically, metallic male fastener components are installed with mating metallic female fastener components to hold the parts together. The metallic male fastener components include, for example, threaded pins or lockbolts. The metallic female mating components may take the form of threaded collars, nuts, and/or swaged collars. Use of metallic components, however, increases the weight of the aircraft. Currently, the mechanical joining of non-metallic or composite aircraft components using metallic fasteners have been the excepted industry standard.
The use of non-metallic composite materials or even a hybrid of both metallic and non-metallic composite material components in mechanical fastener assemblies for joining non-metallic composite structural components to each other have been very limited or non-existent. The reasons for these limited uses include, for example, material property limitations, such as plastic deformation. The deformation aspects or considerations may include deformability in mating collars of two-piece systems such as lockbolts or threaded pins. Lower shear strength, galvanic corrosion, and limited compressive strength are examples of other factors that have limited the use of composite materials in fastener components.
Even with the use of large co-cured composite structures in aircraft construction, the joining of composite components using mechanical systems are still desirable especially for areas in the aircraft where the need for repair and/or replacement of the structural components is foreseen or unavoidable.
As a result, manufacturers still seek to improve fastening technology to increase levels of automation, ease of assembly, and cost and weight savings as well as other factors. Therefore, it would be advantageous to have improved fastening systems using composite materials to decrease the weight while improving the performance of the aircraft.